Paper feed mechanism



14, 1962 R. E. WILKINS 3,049,276

PAPER FEED MECHANISM Filed Oct. 21, 1960 INVENTOI? ROBERT E. W/LK/NS ATTORNEY Uite States Patent Ofifice 3,@49,Z76 Patented Aug. 14, 1952 3,049,276 PAPER FEED lvIEtZHANlSlvl Robert E. Wilkins, Wollaston, Mass, assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Mind, a corporation of Delaware Filed Got. 21, 196i Ser. No. 64,030 12 Claims. (Cl. 226-74) This invention relates in general to a new and improved web feed mechanism, in particular to a paper feed mechanism for a high-speed printer in which the paper is advanced past a print station under tension.

Present-day high-speed printers which are capable of printing speeds of the order of 1,000 lines per minute require a paper feed mechanism which is capable of advancing the paper web rapidly past the print station while maintaining accurately controllable tension in the web. Proper paper tension is important in order to obtain a printed product of high quality.

In the case where the paper web is advanced by means of perforations along its edges which are engaged by the pins of a pair of synchronously moving tractors stationed on opposite sides of the print station, the paper tension may be conveniently adjusted while the paper feed operation is in progress by varying the relative phase of the tractors. Where one of the tractors is belt-coupled to its drive source with the belt linkage forming a pair of opposite belt sections which engage the tractor drive gear, the coupled drive tractor may be advanced or retarded relative to the other tractor by lengthening one of the aforesaid opposite belt sections at the expense of the other one.

Another technique for accomplishing the same result is to shift the points at which the aforesaid opposite belt sections engage the periphery of the drive gear. If one considers that the belt sections are roughly symmetrical with respect to a center line through the tractor drive gear axis, any angular rotation of the center line about the axis will shift the points of tangency of the belt sections about the periphery of the drive gear. Since one of the belt sections now engages the drive gear earlier than before while the other belt section engages the drive gear later, the phase of the tractor With respect to the other tractor is shifted.

Past attempts at implementing a satisfactory tractor phasing arrangement in a paper feed mechanism of the type described have been largely unsuccessful. The manipulation of the opposite belt sections which couple the tractor drive gear to the driving source in prior art devices inevitably produces excessive belt tension in at least one of these belt sections. In some prior art devices, the total length of the belt linkage path actually varies during the aforesaid manipulation and produces excessive belt tension and slack. More commonly, however, the tension in a single belt section becomes temporarily excessive in presently available equipment, but is equalized in one complete traversal of the belt path. The unequal belt tension which exists during this interval may produce permanent stretching of the belt. Moreover, the added belt tension, however temporary, places an additional strain on the bearings of the driving source and of the tractor drive gear and is instrumental in producing vibrations.

Accordingly, it is the primary object of this invention to provide a few feed mechanism for a high-speed printer which overcomes the foregoing disadvantages.

It is another object of this invention to provide an i1n proved web feed mechanism for a 'higl-speed printer wherein the tension of the web is accurately controllable.

It is a ,further object of this invention to provide a paper web feed mechanism for a high-speed printer wherein the relative phase of a pair of paper advancing means may be varied by manipulating the belt linkage of one of them without producing excessive belt tension.

It is an additional object of this invention to provide a webbed feed mechanism for a high-speed printer which is simple and economical in construction and which permits accurate control of the tension of the web.

The foregoing objects are carried out in the present invention by manipulating the belt linkage of one of a pair of synchronously operating tractors which cooperate to advance the paper web past an inter-mediately positioned print station. The belt linkage comprises a pair of opposite facing belt sections which move in opposite directions and which engage the drive gear of the manipulated tractor. Each belt section threads separate guide means stationed between the driving source and the drive gear. The guide means may be jointly moved so that the path of one belt section is effectively lengthened at the expense of the path of the other belt section, while the points of tangency of both belt sections are simultaneously shifted around the periphery of the tractor drive gear. The symmetrical manner in which the guide means operate on the belt linkage prevents excessive belt tension from occurring with the associated adverse effects discussed above.

The various novel features which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its advantages and specific objects thereof, reference should be had to the following detailed descriptions and the accompanying drawing, the single FIGURE of which illustrates a preferred embodiment of the invention.

With reference now to the drawing, suitable perforations along the edges of a continuous paper web 10 are engaged by the pins of a pair of tractors 12 and 14 respectively, which are spaced on opposite sides of a print station 15. A pair of fixed paper guides 18 and 20 is disposed between the tractors 12 and 14 respectively and the print station to provide the proper position at the print station. The tractor 12 is seen to consist of a tractor drive gear 22 having a coaxial portion 24 of reduced diameter. An idler gear 26 is spaced from the drive gear 22 and cooperates with the portion 24 of the latter to drive an endless tractor chain 28. In similar manner, the tractor 14 comprises a tractor drive gear 32 whose reduced diameter portion 34 cooperates with a spaced idler gear 36 to drive another endless tractor chain 38. The tractor chains 28 and 38 carry the aforesaid pins which engage the perforations of the continuous paper web 10.

The drive source for both tractors is seen to be a drive wheel 4% which is adapted to rotate about a pivot 54 and is powered from a motor 42. The tractor drive gear 22 is coupled to the drive wheel 49 by means of a belt linkage 42. A belt linkage 44 which includes a pair of opposite belt sections 46- and 48 respectively couples the tractor drive gear 32 to the drive wheel 40. The opposite belt sections 46 and 48 engage the drive gear 32 at the points of tangency 51 and 53 respectively. These tangency points, as well as the opposite belt sections themselves, are roughly symmetrical with respect to a center line 49 passing through the pivot 52. A supporting plate 5% is rotatably positioned about a pivot 56 between the tractor drive gear 32 and the drive wheel 40, the pivots 52 and 54 respectively of the latter being aligned with the pivot 56. Two pairs of rotatable pulleys 53, 60 and 62, 64 are symmetrically positioned on the supporting plate 50 with respect to the pivot 56 of the latter. The supporting plate 5% further includes a geared peripheral section 66 which engages a worm gear 68. The

worm gear is rotatably supported in a bracket 79 and includes an extension 72 which terminates in an adjusting knob 74.

The belt section 46 is seen to thread the pulleys 53 and 60 which are in contact with the opposite sides of the belt section. The pulleys produce substantially opposite deflections of the path of the belt section 46 which is seen to be divided into a pair of laterally displaced path portions 46a and 46b. The magnitude of the displacement is determined by the length of a third portion 460 of the belt section 46. In similar manner, the belt section 48 threads the pulleys 62 and 64 in a manner where the deflections produced by the pulleys divide it into a pair of laterally displaced path portions 43a and 48b. The magnitude of the path displacement is determined by the length of a third path portion 430. It will be noted that the lateral displacements of the belt sections 46 and 48 intermediate their paths are of opposite direction.

In operation, the tractors 12 and 14, being directly coupled to the same driving source, rotate in synchronism to advance the paper web past the print station 16 in the direction of the arrow 80. The corresponding direction of rotation of the drive wheel 40, the tractor drive gears 22 and 32, as well as the direction of motion of the respective belt linkages, is indicated in the drawing by means of appropriate arrows. I If it is desired to increase the paper tension, the tractor drive gear 32 must be advanced with respect to the tractor drive gear 22, i.e. it must be rotated in a counterclockwise direction. In order to accomplish this object, the belt sections 46 and 48 are manipulated by rotating the common supporting plate in a clockwise direction. This rotation is carried out by turning the knob 74, whose turning motion is applied to the worm gear 68 to rotate the supporting plate about its pivot 56. As the rotation of the supporting plate proceeds, the position of the pulleys 58 and with respect to each other changes in a manner to decrease the lateral displacement of the portions 46a and 46b, determined by the length of the portion 460. Since the path of the belt section 46 has been shortened without decreasing the length of the belt section itself, an excess amount of belt sections results. In effect, the belt section 46 is thereby lengthened. Simultaneously, the lateral displacement of the path portions 48a and 48b is increased (as measured by the length of the path portion 48c) by an amount equal to the corresponding decrease in the belt section 46. This results in a corresponding increase in the path length of the belt section 48, in effect shortening the latter. The additionally required length of belt section is, of course, obtained from the excess of the belt section 46 since the two actions proceed simultaneously and they are equal in the degree of change brought about.

In the drawing, the belt sections 46 and 48 are shown as being symmetrically disposed with respect to the center line 49 which passes through the pivot 52 of the tractor drive gear 32. As previously explained, this position determines the points of tangency 51 and 53 where the belt sections 46 and 48 respectively engage the drive gear 32. When the common supporting plate 50 is rotated in a clockwise direction, the pulleys 58 and 60 are moved out of the path of the belt section 46 by an amount depending upon the magnitude of the angular rotation of the supporting plate.

The result of this movement is to shift the tangency point 51 in a counterclockwise direction along the periphery of the drive gear 32. Simultaneously, the pulleys 62 and 64 are increasingly rotated into the path of the belt section 48 so that the tangency point 53 is shifted by a corresponding amount in the same direction along the periphery of the tractor drive gear 32. The effect may be visualized by rotating the center line 49 in a counterclockwise direction about the tractor drive gear pivot 52, the belt sections 46 and 48 remaining symmetrically disposed with respect thereto. The incoming belt section 46 will be seen to engage the periphery of the tractor drive gear 32 at a later point in time, and the outgoing belt section 48 leaves the tractor drive gear 32 at a later point in time.

The results of effectively lengthening the belt section 46 at the expense of the belt section 48, and of the shift of the tangency points 51 and 53 in a counterclockwise direction along the periphery of the track drive gear 32, combine to advance the position of the drive gear 32 in a counterclockwise direction with respect to the drive gear 22 whose position is una fected. Accordingly, the phase of the tractor 14 is advanced with respect to that of the tractor 12 in order to Obtain increased tension in the continuous paper web 10.

Owing to the symmetry of the pulleys with respect to the pivot 56 of the supporting plate 56, the efiect on the belt sections 46 and 43 of rotating the supporting plate are precisely balanced. Thus, in the case of the clockwise rotation of the supporting plate which was explained above, the decrease in the lateral displacement of the pat portions 46a and 46b is precisely offset by the increase in the lateral displacement of the path sections 48a and 48b. Similarly, the shift of the tangency point 51 in a counterclockwise direction along the periphery of the tractor gear 32 is offset by a corresponding shift in the counterclockwise direction of the tangency point 53. It will be appreciated that the reverse situation is true if the common supporting plate 50 is rotated in the counterclockwise direction in order to decrease the tension of the paper web 10 by retarding the phase of the tractor 14 with respect to that of the tractor 12. In either case, excessive tension is avoided in the belt sections 46 and 48 respectively so that belt stretching, vibrations and undue strains on the pivots 52 and 54 from this source are eliminated.

The invention is not confined to the illustrated preferred embodiment and is subject to diiferent modifications as the needs of the particular printer in which the mechanism is employed may dictate. For example, the tractor drive gears 32 and 22 need not be driven from a common source, provided only that they rotate in synchronism with each other. Where a common drive source is used, the drive gear 22 may be directly geared to the drive source if desired. It will be further understood that the relative phase of the two tractors determines the tension in the paper web. Accordingly, it may be desirable to operate on both tractors in order to vary their relative phase.

The belt sections 46 and 48 need not thread their respective pulley pairs in the manner shown. Thus, the belt section 46 may engage the pulley 60 on its undersurface in the drawing and contact the pulley 58 on its upper surface. A corresponding change is required with respect to the pulleys 62 and 64. In the latter case, given the indicated direction of web travel, the clockwise rotation of the supporting plate 50 will produce slack in the paper web while a counterclockwise rotation'will produce greater tension.

It will also be understood that fixed guides, attached to the common supporting plate, could be substituted for the rotatable pulleys. It is also possible to have the guide pairs movably disposed separately of each other, provided only that a simultaneous manipulation of the belt sections may be effected in equal amounts.

It will be apparent from the foregoing disclosure of the invention that numerous modifications, changes and equivalents will now occur to those skilled in the art, all of which fall Within the true spirit and scope contemplated by the invention. What is claimed is:

1. In a web feed mechanism for a high-speed printer including first and second spaced web advancing means and means for driving said web advancing means in synchronismwith each other, at least one of said driving means including a belt linkage having a pair of oppositebelt sections, means for adjusting the tension of said web comprising, means disposed on a common support to eifect substantially opposite, intermediate deflections of the path of each of said belt sections, and means for selectively positioning said common support to produce opposite changes of the lengths of said paths to vary the relative phase of said web advancing means.

2. In a web feed mechanism for a high-speed printer having first and second web advancing means adapted to invariantly engage said web and to operate in synchronism with each other, at least one of said web advancing means being coupled to a power source by a belt linkage including a pair of opposite belt sections, each of said belt sections having a pair of opposite sides, a web tension adjustment comprising guide means engaging said opposite sides of each of said belt sections which link said one web advancing means, said guide means effecting a substantially lateral displacement of the path of each of said belt sections by producing substantially opposite deflections of the latter, and means for simultaneously eifecting opposite changes of said displacements to vary the phase of said one Web advancing means with respect to the other one.

3. In a web feed mechanism having first and second Web advancing means adapted to invariantly engage said web and to operate in synchronism with each other, at least one of said web advancing means being coupled to a power source by a belt linkage including a pair of opposite belt sections which extend to a pair of contact points on said one web advancing means, each of said belt sections having a pair of opposite sides, a web tension adjustment comprising guide mean engaging said opposite sides of each of said belt sections which iink said one web advancing means, and means for varying the position of said guide means to shift said contact points of said opposite belt sections on said one web advancing means in a chosen direction while increasing the effective length of a selected one of said opposite belt sections at the expense of the other one.

4. In a web feed mechanism for a high-speed printer having first and second web advancing means adapted to operate in synchronism with each other, at least one of said web advancing means being coupled to a power source by a belt linkage including a pair of opposite belt sections, a web tension adjustment comprising a pair of guide means disposed on a common support and engaging opposite sides of each of said belt sections which link said one web advancing means, said guide means being positioned to produce substantially opposite displacements of the paths of said belt sections, and means for moving said common support to effect simultaneous, opposite changes of said displacements to vary the relative phase of said web advancing means.

5. In a web feed mechanism having first and second web advancing means adapted to operate in synchronisrn with each other, at least one of said web advancing means being coupled to a power source by a belt linkage including a pair of opposite belt sections, a web tension adjustment comprising a common support rotatably disposed about a pivot, a pair of guide means symmetrically positioned on said support with respect to said pivot, each of said guide means engaging opposite sides of one of said belt sections which link said one web advancing means, said pair of guide means being positioned to produce substantially opposite displacements of the paths of said belt sections, and means for rotating said common support to effect opposite changes of said displacements to vary the relative phase of said web advancing means.

6. In a web feed mechanism having first and second web advancing means adapted to Operate in synchronism with each other, at least one of said web advancing means being coupled to a power source by a belt linkage including a pair of opposite belt sections which extend to a pair of contact points on said one web advancing means, a web tension adjustment comprising a common support rotatably disposed about a pivot, a pair of guide means symmetrically positioned on said support with respect to said pivot, each of said guide means engaging opposite sides of one of said belt sections which link said one web advancing means, said pair of guide means being positioned to produce substantially opposite displacements of the paths of said belt sections, and means for rotating said common support to shift said contact points of said opposite belt sections on said one web advancing means in a chosen direction while increasing the effective length of a selected one of said opposite belt sections at the expense of the other one.

7. In a paper feed mechanism for a high-speed printer having first and second spaced paper advancing means adapted to operate in synchronism with each other, at least one of said paper advancing means being coupled to a power source by a belt linkage including a pair of opposite belt sections, a paper tension adjustment comprising a supporting plate rotatably disposed about a pivot, two pairs of rotatable belt guides symmetrically positioned on said supporting plate with respect to said pivot, the guides of each of said pairs being positioned to engage opposite sides of respective ones of said belt sections which link said one paper advancing means to effect a substantially lateral displacement of the belt section path, said guide pairs displacing the paths of said belt sections in substantially opposite directions, said supporting plate further including a geared portion, and means engaging said geared portion for selectively rotating said supporting plate about its pivot, said rotation being adapted to effect opposite changes of said path displacements to vary the relative phase of said paper advancing means.

8. A mechanism for feeding paper past the print station of a high-speed printer, comprising first and second tractors stationed on opposite sides of said print station each invariantly adapted to engage said paper, means for driving said tractors in synchronism, the driving means associated with at least one of said tractors including a belt linkage having a pair of opposite belt sections, each of said belt sections having a pair of opposite sides, a paper tension adjustment including guide means engaging said opposite sides of each of said belt sections which link said one tractor, said guide means being positioned to provide an increment of the path length of each of said belt sections by means of substantially opposite deflections of the latter, and means for simultaneously effecting opposite changes of said increments to vary the phase of said one tractor with respect to the other one.

9. A mechanism for feeding paper past the print station of a highspeed printer, comprising first and second tractors stationed on opposite sides of said print station each invariantly adapted to engage said paper, means for driving said tractors in synchronism, the driving means associated with at least one of said tractors including a tractor drive gear coupled by a belt linkage having a pair of opposite belt sections which extend to first and second points of tangency on said drive gear, each of said belt sections having a pair of opposite sides, a paper tension adjustment including guide means engaging said opposite sides of each of said belt sections which link said one tractor, said guide means being positioned to provide an increment of the path length of each of said belt sections by means of substantially opposite deflections of the latter, and means for varying the position of said guide means to shift said points of tangency of said opposite belt sections in a chosen direction about the periphery of said drive gear while increasing the effective length of a selected one of said opposite belt sections at the expense of the other one.

10. A paper feed mechanism for a high-speed printer comprising first and second tractors stationed on opposite sides of a print station, each adapted to engage said paper, means for driving said tractors in'synchronism, the driving means associated with at least one of said tractors including a tractor drive gear coupled by a belt linkage having a pair of opposite belt sections which extend to first and second points of tangency on said drive gear, a paper tension adjustment including a supporting plate rotatably disposed about a pivot, two pairs of rotatable belt guides symmetrically positioned on said supporting plate with respect to said pivot, the rotatable guides of each of said pairs being positioned to engage opposite sides of respective ones of said belt sections which link said one tractor to effect a substantially lateral displacement of the belt section path, said guide pairs displacing said paths in substantially opposite directions, said supporting plate further including a geared portion, means engaging said geared portion for selectively rotating said supporting plate about its pivot point, said rotation producing opposite changes of the magnitudes of said path displacements; whereby said points of tangency of said opposite belt sections are shifted in a chosen direction about the periphery of said drive gear while the length of a selected one of said pair of opposite belt sections is increased at the expense of the other one.

11. A paper feed mechanism for a high-speed printer comprising first and second tractors stationed on opposite sides of a print station, each adapted to engage said paper, means for driving said tractors in synchronism, the driving means associated with at least one of said tractors including a belt linkage having a pair of opposite belt sections, a paper tension adjustment including a supporting plate rotatably disposed about a pivot, said pivot being symmetrically positioned between said opposite belt sections, two pairs of rotatable belt guides symmetrically positioned on said supporting plate with respect to said pivot, the rotatable guides of each of said pairs being positioned to engage the opposite sides of respective ones of said belt sections which link said one tractor to effect a substantially lateral displacement of the belt section path, said guide pairs displacing said paths in substantially opposite directions, said supporting plate further including a geared portion, a worm gear engaging said geared portion for selectively rotating said supporting plate about its pivot point, said rotation producing opposite changes of said path displacements to vary the phase of said one tractor with respect to the other one.

12. A high-speed printer feed mechanism for advancing a perforated paper web past a print station, comprising first and second tractors positioned at the entrance and exit sides respectively of said print station, each of said tractors including rotatable drive and idler gears and an endless tractor chain driven by said gears, said tractor chain being adapted to engage the perforations of said paper web, a drive wheel coupled to a drive motor, an endless belt comprising a pair of opposite belt sections coupling each of said tractor drive gears to said drive wheel, said belts being adapted to drive said tractors in the same direction, a supporting plate positioned intermediate said drive wheel and the drive gear of said second tractor, said supporting plate being rotatably disposed about a pivot symmetrically positioned between said opposite belt sections, a worm gear, a circumferential section of said supporting plate being adapted to engage said worm gear, means for selectively turning said worm gear to rotate said supporting plate about its pivot, two pairs of rotatable pulleys symmetrically positioned on said supporting plate on opposite sides of said pivot, each of said pulley pairs being threaded by one of said opposite belt sections which link said second tractor drive wheel, said pulley pairs dividing each of said threading belt sections into separate portions laterally displaced from each other in mutually opposite directions, the rotation of said supporting plate about its pivot point effectively increasing the magnitude of one of said lateral displacements at the expense of the other displacement to change the phase of said second tractor drive wheel relative to that of said first tractor drive wheel.

Frazer-Nash et a1. May 2, 1944 Sorkin May '16, 1944 

